When using the left turn signal it turns on the right blinker, when using the right turn signal sometimes it works, sometimes it doesnt. It's not as bad with the steering wheel up all the way, but still does it, and some days it works normal.

 

Not sure if it applies to you, but I got something in the mail that extended the warranty on the turn signal control to 100,000 miles. It mentioned that it might cause the signals to work in reverse. Might be worth a call.

 

Bad multi-function switch.

 

I had same issue. check your trailer plug and wires. Undo the clip on back look at connections. Mine was all green replaced the whole set up. Never happened again.

 

Check out this "How To ..." that member Shorts posted. It may help with your problems.
https://www.dieseltruckresource.com/d...44#post3131344